Structure of Woody Plants
Vascular Cambium
Initiation of the Vascular Cambium
Vascular Cambium
meristem that produce the secondary plant body
Fascicular cambium
cells continue to divide instead of maturing
Interfascicular cambium
parenchyma cells that come our of cell cycle arrest and resume mitosis
Fusiform Initials
Periclinal wall
wall parallel to the circumference of the cambium
anticlinal walls
vascular cambium cells that divide longitudinally
Ray initials
Arrangement of Cambial Cells
Storied Cambium
Rows of regular horizontal fusiform initials
Nonstoried cambium
Rows of fusiform initials without horizontal pattern
Secondary Xylem
Types of Wood Cells
Secondary xylem (wood)
cells formed interior of the vascular cambium
axial system
derived from the fusiform initials
radial system
develops from the ray of initials
Hardwoods
angiosperm woods containing large amounts of fibers
Softwoods
Woods that contain few or no fibers
Growth Rings
Early wood
wood that is first formed
Late wood
cuticle has thickened, less transpiration, large numbers of new vessels.
Annual ring
have heavy fibers and thick secondary walls
growth ring
when a tree fails to grow and produce a ring
diffuse porous
vessels located throughout the growth ring
ring porous
vessels are restricted mainly to early wood
Heartwood and Sapwood
Heartwood
center part of the wood that is always a darker color
Sapwood
Lighter moister outer region of the center of a log
tylosis
wood parenchyma cells push bubbles of protoplasm through the pits into the vessel, forming a plug
Reaction Wood
Reaction wood
plants response to stress such as drooping
Secondary Phloem
secondary phloem
formed from vascular cambium just as secondary xylem is, it too has has an axial and a radial system
Axial system
Size, shape , and number of phloem rays match xylem rays
is in charge of conduction up and down the stem or roots
phloem rays are even more so important for secondary phloem construction than that of xylem rays
Outer Bark
Cork and Cork Cambium
Cork Cambium (phallogen)
Cork Cell (Phellem cell)
formed from secondary phloem
outer cell after cell division
Phelloderm
mature layer of parenchyma cells from the cork cambrium
Periderm
Cork Cambium, layers of cork cell, and phelloderm
Outer Bark
all tissues outside the innermost cork cambium
Inner Bark
all secondary phloem between the vascular cambium and the innermost cork cambium
Lenticels and Oxygen Diffusion
Lenticels
Region of aerenchymatous cork
Initiation of Cork Cambium
Anomalous Forms of Growth
Secondary Growth in Roots
Anomalous Secondary Growth
alternative cambia produced by secondary bodies that differ from common type
Unusual Primary Growth
Established growth
increase in width and addition of adventitious roots in palms
